The agency recently released a request for information that will seek to identify weapon concepts for defense against future advanced threats such as hypersonics, he said. The responses are due Friday and will be used to develop an “analysis of alternatives” planned for 2017.

Hypersonic missiles are under rapid development in China and Russia as a way to penetrate advanced air and missile defenses such as those developed by the Army and Navy. A major problem for current U.S. missile defenses is that all were designed from the ground up to target missiles with predictable and unchanging trajectories.

China’s DF-ZF hypersonic glide vehicle has been tested at least seven times, and Russia’s Yu-71 hypersonic strike weapon also has been tested several times. The gliders are launched atop ballistic missiles and travel along the edge of the atmosphere at speeds from Mach 5 to Mach 10 — 3,800 to 7,600 miles per hour.

The maneuvering strike vehicles can defeat all current U.S. missile defenses, including ground-based interceptors in California and Alaska, sea-based Aegis anti-missile systems and the land-based Terminal High Altitude Area Defense, or THAAD.

Congress has been pushing the Pentagon to deal with the threat. The most recent defense authorization bill signed into law in December requires the Pentagon to create a dedicated office for emerging hypersonic missile threats.

The MDA disclosed the advanced missile threat study in a brief federal notice published last month.

A recent study by a panel of Air Force experts warned last fall that the U.S. is falling behind in the hypersonic missile race.

“The People's Republic of China and the Russian Federation are already flight-testing high-speed maneuvering weapons (HSMWs) that may endanger both forward-deployed U.S. forces and even the continental United States,” the study said. “These weapons appear to operate in regimes of speed and altitude, with maneuverability that could frustrate existing missile defense constructs and weapon capabilities.”

The study concluded that there was “no formal strategic operational concept or organizational sense of urgency” regarding the threat. It also faulted what it called the Pentagon’s “lack of leadership” in developing countermeasures and defense solutions.

MALAYSIANS TRY TO IDENTIFY TOXIN IN NORTH KOREAN HIT

Authorities in Malaysia are trying to identify the poison used in the apparent assassination of the estranged brother of North Korean leader Kim Jong-un.

Kim Jong-nam, Mr. Kim’s half brother, was killed Feb. 13 in Kuala Lumpur International Airport by a woman who approached him and put some type of substance on his face. The incident was captured on airport surveillance video.

Kim died on the way to a hospital after complaining that something had affected his vision.

Four people, including a North Korean, were arrested, and police have identified four other North Koreans who left the country shortly after the attack.

Kim Jong-nam, who had been living in Macao under Chinese government protection for the past five years, was regarded as a potential threat to the rule of the North Korean dictator, according to Asia analysts.

Kim Jong-un has purged several hundred officials since taking power in late 2011. Among those killed: his uncle, Jang Sang-taek, who was regarded as too close to China by the leader.

Noor Hisham Abdullah, Malaysia’s director general of health, told reporters Tuesday that poison has not been ruled out in the attack. However, initial analysis could not identify a toxin. “We have to confirm with the lab report before we can make any conclusive remark,” he said, adding that additional forensic analysis is underway.

On Wednesday, Malaysia’s chief of police, Khalid Abu Bakar, said two North Korean suspects in the attack worked within the North Korean Embassy in Malaysia. A third suspect worked for the North Korea’s state airline.

Mr. Bakar also said security surrounding Kim’s body was increased after an attempted break-in at the hospital mortuary this week.

North Korea has demanded a return of the body without an autopsy.

If investigators link North Korea to the killing, it could lead to once again placing Pyongyang on the list of state sponsors of terrorism. North Korea was placed on the terrorism list for its intelligence operations in conducting deadly bombings and killings abroad. The country was removed from the list in 2008 by President George W. Bush as part of the failed effort to negotiate an end to North Korea’s nuclear programs.

PACOM COMPLAINS OF LEGAL RESTRAINTS

Adm. Harry Harris, commander of the Pacific Command, complained this week that the military is facing too many legal constraints in efforts to develop high-technology forces and capabilities.

Speaking at a conference in San Diego on Tuesday, Adm. Harris urged abandoning “linear thinking” on weapons and war fighting in favor of building deadlier, more revolutionary types of arms.

“Engineers and acquisitions types will hear this message and think, ‘The PACOM commander is tired of the same old stuff. He’s demanding innovative weapon systems with more lethality.’ You’d be right,” he said.

The four-star admiral wants the military to build weapons that will produce exponential leaps in firepower, using cutting-edge technology such as drones and artificial intelligence.

New concepts will include what Adm. Harris called the “Ghost Fleet” of unmanned and autonomous systems on land, in the air and under water working together with older weapons. The admiral added that some of the major obstacles to retooling arms and war fighting concepts are self-imposed.

“In the vernacular, we need to stop shooting ourselves in the foot,” he said.

For example, “unnecessary restrictions” currently are imposed on cyberwarfare capabilities and the authorities needed to use them.

“You’ve all seen the headlines, ‘Cyber capabilities exceed authorities.’ I read that to mean that ‘we can’t use the tools we’ve developed.’ And I’m sure some of the developers of these tools are wondering why they even bother to continue their innovative work if we can’t use it,” he said.

Another significant restriction has been imposed on developing weapons needed to counter growing cruise and ballistic missile threats in Asia, from both North Korea and China.

“China is free to field a complete arsenal of highly capable advanced land-based anti-ship missiles while we’re restricted from fielding the kinds of conventional weapons we must have to stay ahead of them,” said Adm. Harris, noting Russia’s recent deployment of an illegal cruise missile in violation of a 1987 nuclear treaty.

He called for applying innovative thinking on how to deploy forces while adhering to international treaties.

“Or, if we’re not going to get exponentially smart, let’s at least get better lawyers,” he said.

Adm. Harris said as a military commander he seeks to bring a gun to a knife fight. But he warned that current restrictions mean that “I might get shot before I even get to the fight.”

“I can’t ask you to build something that we can’t use,” he said. “But we can’t leave game-changing technology on the shelf because of restrictions on sensible security measures.”